1. Field of the Invention
The invention relates to spun V-grooved sheet metal pulleys in which one or more V-grooves are formed in an annular flange or side wall of a cup-shaped blank, in which the V-grooves are relatively narrow and relatively deep, and in which the pulley noise level in operation is reduced.
More particularly, the invention relates to the provision of noise dampening means trapped and locked under tension between layers of a double flange fold of a pulley V-groove wall; or to the provision of noise dampening means tension-engaged against an inside surface of at least one of the V-groove walls of the V-groove pulley.
2. Description of the Prior Art
Single and multiple V-grooved sheet metal pulleys, particularly those of the type having the pulley grooves spun in a cylindrical side wall of a sheet metal cup of innumerable sizes and cross-sectional configurations, have been used extensively for many years, such as the pulleys shown in U.S. Pat. Nos. 2,685,856, 2,827,225, 2,869,223, and 3,852,863.
Such pulleys in operation, particularly under heavy belt loads and at certain speeds, have been found to develop a natural resonant frequency of vibration which produces a ringlike or whining noise, which is objectionable, particularly in the operation of motor vehicles.
Many expedients have been tried in attempts to reduce or dampen the noise level of such pulleys during operation; but prior to the invention, no satisfactory answer to such noise problem has been found of which I am aware.
Accordingly, there has been an existing need for many, many years for a spun dynamically-balanced single or multiple V-grooved sheet metal pulley in which the noise level resulting from vibration frequency of the pulley at certain speeds under heavy belt loading can be eliminated or reduced to an unobjectionable minimum level.